On Thu, 21 Dec 2023 01:34:56 +0900 Masami Hiramatsu (Google) <mhira...@kernel.org> wrote:
> On Tue, 19 Dec 2023 13:54:18 -0500 > Steven Rostedt <rost...@goodmis.org> wrote: > > > From: "Tzvetomir Stoyanov (VMware)" <tz.stoya...@gmail.com> > > > > There are two approaches when changing the size of the ring buffer > > sub page: > > 1. Destroying all pages and allocating new pages with the new size. > > 2. Allocating new pages, copying the content of the old pages before > > destroying them. > > The first approach is easier, it is selected in the proposed > > implementation. Changing the ring buffer sub page size is supposed to > > not happen frequently. Usually, that size should be set only once, > > when the buffer is not in use yet and is supposed to be empty. > > > > Link: > > https://lore.kernel.org/linux-trace-devel/20211213094825.61876-5-tz.stoya...@gmail.com > > > > OK, this actually reallocate the sub buffers when a new order is set. > BTW, with this change, if we set a new order, the total buffer size will be > changed too? Or reserve the total size? I think either is OK but it should > be described in the document. (e.g. if it is changed, user should set the > order first and set the total size later.) > Patch 11 keeps the same size of the buffer. As I would think that would be what the user would expect. And not only that, it breaks the latency tracers if it doesn't keep the same size. -- Steve
